Emil koster



UNITED STATES PATENT OFFICE.

EMIL KOSTER, OF NEUMI INSTER, GERMANY, ASSIGNOR TO EDUARD AVELLIS, OF BERLIN, GERMANY.

PROCESS OF TREATING LEATHER PREPARATORY TO DYEING.

SPECIFICATION forming part of Letters Patent No. 591,769, dated October 12, 1897. Application filed August 8, 1896. Serial No. 602,195. (No specimens.)

T0 ctZZ whom it may concern:

Be it known that I, EMIL KosTER, a subject of the King of Prussia, German Emperor, residing at Neumiinster, Holstein, in the German Empire, have invented certain new and useful Improvements in Processes of Treating Leather Preparatory to Dyeing, of which the following is a specification.

The object of the present invention is to prepare chrome tanned leather in such a manner that it can be dyed by means of anilin. colors in all shades. This is mainly accomplished by neutralizing the chrome tanned leather and treating it with substances con taining tannin. For the purpose of obtaining a clear color it is advisable to give the leather an additional treatment with tartar emetic or tartar-emetic preparation.

In practice the process is carried out as follows: About two hundred pounds of chrome leather are treated with six pounds of precipitated chalk and four pounds of common commercial salt stirred into about one hundred quarts of water, and in this solution the leather is washed for about one-quarter of an hour, until all acid has been removed. This can be ascertained by means of litmus-paper. The leather is then washed in water to remove the chalk. The leather that has thus been neutralized is then treated with substances containing tannin. In case divi-divi is used I prefer to use one pound of tanning substance to one hundred pounds of leather, the tanning substance being used as a solution of from 1 to 2 Baum. For lighter shades weaker solutions are used. The leather remains in this solution for about half an hour, until the surface is properly colored.

The leather that has been so treated can be dyed at once, but it is advisable to first treat it with tartar emetic in order to obtain clear colors-for chrome sheep and goat skins one gram of tartar emetic for three liters of fluid for each skin, for calfskins one and one-half to two grams for from four, five, to six liters, (according to the size of the skin,) and for oxhides six to ten grams of every ten to eighteen liters.

The solution is used at 30 Celsius. The leather remains in the working barrel or vat for from five to six minutes. The treated skins are rinsed in clear water and are then dyed in a vat with the desired color. I

Having thus described my invention, the following is what I claim as new therein and desire to secure by Letters Patent:

1. The process of preparing acid chrome leather for dyeing consisting in neutralizing the skins, with a solution of chalk and salt, then washing in water to remove the chalk,

then treating them with substances containing tannin, and then treating them with tartar emetic, substantially as herein set forth.

2. The process of treating chrome leather for dyeing, consisting in neutralizing the leather, then treating it with substances containing tannin and then treating it with tar tar emetic, substantially as herein shown and described.

In witness whereof I have hereunto set my hand in presence of two witnesses.

EIWIIL KOSTER.

Witnesses PERREGRINE VARNALS, KATE STYLES. 

